Accurately timed gestations in Rhesus monkeys are used. Streptozotocin, 40-48 mg/kg is administered intravenously to the adult female prior to or in the first trimester of pregnancy. This drug induces a glucose intolerant state secondary to pancreatic beta cell destruction. During the third trimester, acute experiments are performed under general anesthesia and aseptic surgical techniques. Cannulae are placed into both the maternal and fetal circulations to permit sequential sampling of blood. The responsiveness of the fetal/maternal pancreatic beta and alpha cells and other organ systems are examined. In some instances the same questions are asked in the newborn on the first day of life. BIBLIOGRAPHIC REFERENCES: Epstein, M.F., Chez, R.A., Oakes, G.K. and Mintz, D.H.: Fetal Pancreatic Glucagon Responses in Glucose Intolerant Nonhuman Primate Pregnancy. Amer. J. Ob/Gyn, 127: 268-272, 1977. Epstein, M.F., Farrell, P.M., Sparks, J.W., Pepe, G., Driscoll, S.G. and Chez, R.A.: Maternal Betamethasone and Fetal Growth and Development in the Monkey. Amer. J. Ob/Gyn, 127: 261-263, 1977.